While the use of hydrogel body adhesives in the of medical field, such as skin electrodes, transdermal drug delivery and wound healing, has been known for several years, hydrogel body adhesives have been disclosed more recently for use in consumer products such as absorbent articles and human waste-management articles; representative of the latter disclosures are EP 1 025 823 and EP 1 025 866, where certain needs specific for such consumer products waste-management products, are addressed, including secure attachment, painless removal and stability of adhesion in presence of excess moisture.
However a particular problem which has not been addressed in said prior art is the ability of the adhesive to adhere directly to a skin surface which has hair present, particularly areas of dense hair growth such as occurs in, e.g., the genital area. Typically the prior art teaches especially in wound care applications, and for incontinence applications such as ostomy articles to remove the hair follicles present on the skin by shaving for example prior to the application of the adhesive. However, such practices whilst moderately acceptable in medical circumstances are not desirable for products which are intended for everyday use for example absorbent articles such as sanitary napkins or incontinence devices such as human waste management devices. The absence of the hair on the skin thereby allows a gasket to be formed with the skin which is necessary in order to ensure the containment of the excreted fluids within the particular device of usage. The prior art does not however address how such gasketing can be achieved without the indignity of removing hair.
Not only does the presence of hair on the skin increase the difficulty to obtain optimum adherence to the skin of the wearer, in addition due to the adhesion which occurs between the hair and the adhesive itself, which typically involves some embedding of the hair within the hydrogel adhesive gel matrix, the removal of the adhesive from the wearer is also extremely painful and is significantly increased versus a skin surface where any hair present has been previously removed.
Thus is it highly desirable to provide a hydrogel adhesive for adhesion to the skin which adheres on skin surfaces which have hair present and which have a reduced pain level on removal of the adhesive. It is further desirable to provide an adhesive which adheres to the skin of a hair populated skin surface but which only has minimal and preferably substantially no adhesion to the hair itself.
It is further desirable to provide an adhesive which can embedded the hair and adhere directly to the skin, thus providing good gasketing, while still allowing painless removal.
It is still another objective of the present invention to provide an adhesive that exhibits an ability to adhere to skin upon reapplication, particularly multiple reapplication for example when the adhesive is misplaced, whilst still allowing painless removal.
It has now been surprisingly found that the above drawbacks will be substantially alleviated by the use of certain hydrogel adhesives with rheology characteristics as defined hereinafter; through said use, attachment to the skin is secure, even if hair is present, the hydrogel is pleasing to the skin upon application, and yet causes no discomfort upon removal and minimal residues.
Finally it has been found that the benefits of the use and of the hydrogels herein can be applied not only to skin populated with hair, but to more generally to surfaces populated with fibers, and thus the present invention also applies to the use of hydrogel with selected characteristics, for surface care articles.